fix: crash on enabling virtual file support

[sukarn-m]

Fixes #90

[flathubbot]

Started test build 86940

[flathubbot]

Build 86940 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/69600/com.nextcloud.desktopclient.nextcloud.flatpakref

[flathubbot]

Started test build 86942

[flathubbot]

Build 86942 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/69602/com.nextcloud.desktopclient.nextcloud.flatpakref

[sukarn-m]

Test build works on my system.

[flathubbot]

Started test build 87507

[flathubbot]

Build 87507 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/70175/com.nextcloud.desktopclient.nextcloud.flatpakref

[flathubbot]

Started test build 91235

[flathubbot]

Build 91235 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/73914/com.nextcloud.desktopclient.nextcloud.flatpakref

[sukarn-m]

@tilosp Could you please review this?

[tilosp]

#142 sets the plugin dir properly, so the symlinks are probably no longer necessary